Electrolytically copper plating an aluminum wire

ABSTRACT

THE INVENTION RELATES TO AN APPARATUS FOR ELECTROLYTICALLY PLATING WIRE. THE APPARATUS IS PARTICULARLY USEFUL IN COPPER PLATING OF ALUMINUM WIRE AND INCLUDES MEANS WHEREBY THE OUTER LAYER OF ALUMINUM OXIDE MAY BE STRIPPED FROM THE ALUMINUM WIRE IMMEDIATELY PRIOR TO IMMERSION OF THE WIRE INTO THE ELECTROLYTIC SOLUTION SO AS TO INHIBIT THE FORMATION OF ALUMINUM OXIDE COATING OF THE STRIPPED WIRE.

. March 2, 1971 w. D. KELLY v 3,561,596

March 2, 1971 w. D. KELLY 3,567,596

ELECTRQLYTICALLY COPPER PLATING AN ALUMINUM WIRE Filed Aug '19. 1968 3 Sheets-Sheet 3 .gTF

March 2,1971

Filed Aug. ,19, 1968 W. D. KELLY ELECTROLYTICALLY COPPER PLATING AN ALUMINUM WIRE 5 Sheets-Sheet S United States Patent 3,567,596 ELECTROLYTICALLY COPPER PLATING AN ALUMINUM WIRE William D. Kelly, 12 Blodgett St., Clarendon Hills, Ill. 60514 Continuation-impart of application Ser. No. 718,399, Apr. 3, 1968. This application Aug. 19, 1968, Ser.

Int. Cl. C23b /18, 5/48, 5/68 US. Cl. 204-28 3 Claims ABSTRACT OF THE DISCLOSURE This application is a continuation-in-part of mycopending application Ser. No. 718,399, filed Apr. 3, 1968, now abandoned.

This invention relates to electroplating apparatus and more particularly to apparatus for electroplating wire.

It is a general object of the invention to produce a new and improved electroplating apparatus of the character described.

Wire of materials other than copper are coming into increasing use primarily because of the shortage of cop per. The most commonly used substitute metal is aluminum. Because of the lower conductivity of aluminum, wires made of that material must be of larger diameter than copper wires capable of carrying the same amount of electrical current. While it may have occurred to seekers of solutions for the problem that possibly aluminum wire could be provided with a more conductive coating, the fact is that aluminum wire upon formation immediately acquires a coating of aluminum oxide when exposed to air. Aluminum oxide is quite inert and hence inhibits or even prevents the application of a coating of more conductive material thereover by layering or otherwise.

According to the present invention, however, means are provided for producing a copper coating on aluminum wire by use of the electrolytic plating method. In order to make such a system workable, the apparatus of the present invention is arranged so that the coating of aluminum oxide present on aluminum wire is stripped from the underlying aluminum and the stripped wire is immediately immersed in electrolytic solution without being exposed to oxygen. By virtue of the foregoing, a coating of aluminum oxide is not re-formed on the aluminum wire and hence it is in condition to receive the electrolytic coating of copper, with the result that a highly conductive wire composed of a layer of aluminum and a coating of copper thereover is formed.

Accordingly, it is a more specific object of the present invention to produce an apparatus for depositing electrolytically a coating of copper over aluminum wire, wherein the aluminum wire has been stripped of its aluminum oxide coating prior to the plating operation, and wherein the reformation of an aluminum oxide coating prior to the plating step is prevented.

Other and further objects of the invention will become readily apparent from the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a side elevational view of apparatus embodying the invention;

FIG. 2 is an enlarged fragmentary vertical sectional view taken along line 22 of FIG. 1;

FIG. 3 is a horizontal section taken along line 3-3 of FIG. 2;

FIG. 4 is a view like FIG. 1 of a modified form of construction;

FIG. 5 is a horizontal section taken along line 5-5 of FIG. 4;

FIG. 6 is a horizontal section taken along line 6-6 of FIG. 4; and

FIG. 7 is a vertical section taken along line 7-7 of FIG. 4.

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail several embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. The scope of the invention will be pointed out in the appended claims.

Referring now to FIGS. 1-3 in the drawings, there is shown a container 10 having side walls 11 and a bottom 12. A fixture 13 is secured to bottom 12, there being a liquid-proof gasket of resilient material 14 interposed between the fixture and the bottom 12 of the container.

The bottom of the container is provided with an open ing 15 communicating with an opening 16 in the gasket 14, in turn communicating with an opening 17 in the fixture. Wire 19 to be treated is guided into the fixture 13 by guide means 18 and then is led into a die member 20 having an opening 21 less than the diameter of the Wire 19. The fixture is arranged to provide a space 22 between the guide means 18 and the die member 20, and air conduits 23 communicate with this space and are adapted to conduct air under pressure therethrough so as to blow chips of Wire removed by the die 20 out of the space 22. Means in the form of a drum 24 are provided upon which the treated wire 25 is rolled after passing through the container 10. Preferably, the drum 24 is powered so as to draw the wire from a drum or reel (not shown) heneath the container through the fixture 13, the container 11, and then onto the drum 24.

A pair of anodes 26 is located in the container 11 adapted to be immersed in the electrolytic liquid therein and attached to the negative terminals of a source of electrical energy while the wire 19, suitably insulated from ground, is connected so as to be the cathode of the plating system.

In operation, with power applied to the drum 24, the wire 19, guided by the guide means 18, is drawn through the opening 21 in the guide member 20 thereby stripping off the outer aluminum oxide surface of the aluminum wire. Emerging from the die 20, the wire passes immediately into the electrolytic solution in the aligned openings 17, 16, and 15, and then directly into the solution in the container 10. While passing between the electrodes 26, the Wire is given a plating of copper and upon emerging from the plating bath is wound up on the drum 24.

The air conduits 23 serve to remove the aluminum oxide stripped from the wire from space or cavity 22. Inasmuch as the wire is not exposed to the atmosphere after the outer aluminum oxide coating is stripped therefrom, no new coating of such material is permitted to form thereon and the surface is ready to receive the plating of copper thereover.

Referring now to FIGS. 4-7, there is shown a fixture 30 the upper edge 31 of which is to be secured in fluid-tight relation in a container (not shown) such as the container 10. Positioned within the fixture 30 is a pair of bearings 32 and 33 rotatably supporting a die carrier 34 provided with a central opening 35. Secured within the opening 35 is a die 36 having an opening 37 aligned with the opening 35. A drive pulley 38 is secured to the die carrier and arranged to be rotated by a V-belt 39 driven by a source of power (not shown).

The fixture 30 is provided with an end wall 40 having an opening 41 in which a wire guide 42 is positioned for guiding a wire 43 therethrough and into the die 36.

It is often advisable to straighten the aluminum wire before the same is presented to the opening in the die and for this purpose there is provided two pairs of straightening rollers, the first pair 44 being positioned above the second pair of rollers 45, with both pairs of straightening rollers being rotatably mounted within a housing 46 secured to the end wall 40. Wire from a drum or reel, or other source of supply, is fed through a wide 47 in the end of the housing 46, and the finished plated wire 48 is wound upon a take-up drum or other means in a fashion similar to that described in connection with the first embodiment of the invention.

It will be understood, of course, that a container provided with anodes and an electrolytic solution is to be used in connection with the fixture 30 and the rotatable die therein contained.

By using a rotatable die in the manner shown and described, complete removal of the aluminum oxide coating normally found on aluminum wire is assured and inasmuch as the wire is then immediately immersed in the electrolytic solution, there is no possibility of re-formation of the aluminum oxide coating thereon. Therefore, the copper plating which occurs in the electrolytic bath is directly upon the exposed pure aluminum surface of the wire.

While the invention has been shown in several embodiments relating to the copperplating of wire, it will be clear to those skilled in the art that the principles of the invention may be used for plating aluminum tubing. Suitable adjustment in the dies to accommodate tubing, either 4 seamless or otherwise, can be effected to make the illustrated method usable to plate aluminum tubing.

I claim:

1. The method of electrolytically copperplating aluminum wire which comprises, stripping the aluminum oxide coating from aluminum wire and then passing the stripped wire out of contact with the atmosphere directly into an electrolytic solution, and then electrolytically plating copper on the stripped exterior surface of the 'wire.

2. The method of electrolytically copperplating aluminum wire which comprises, passing the wire through a rotating die member to strip the aluminum oxide coating from the wire, passing the stripped wire out of contact with the atmosphere directly into an electrolytic solution, and then electrolytically plating copper on the stripped exterior surface of the wire.

3. The method of electrolytically copperplating a substantially endless aluminum member having a circular cross-section which comprises, continuously passing the member through a die to strip the aluminum oxide coating from the member, passing the stripped member out of contact with the atmosphere directly into an electrolytic solution, and then electrolytically plating copper on the stripped exterior surface of the member.

References Cited UNITED STATES PATENTS 2,061,554 11/1936 Billiter 204-209 2,370,973 3/1945 Lang 204-28X 2,680,710 6/1954 Kenmore et al 204-28 2,871,171 1/1959 Atkinson 204--28X F. EDMUNDSON, Primary Examiner US. Cl. X.R. 204-207 

